One of my code files

<?php
    /**
     * Phoenix Hospitality Management System
     * Phoenix REST API - API Department Repository file
     * Written in PHP using the Slim micro-framework
     *
     * @author Troy L. Marker
     * @version 1.0.0
     * @since 0.5.0
     * @copyright Copyright (c) 2020-2021 By Troy Marker Enterprises
     *
     * Declare name space and Import needed functions/classes
     */
    namespace App\Domain\Repository;

    use PDO;

    /**
     * This class provides a repository to the departments Database table
     */
    class Department {

        protected $connection;

        /**
         * Class constructor
         * @param PDO $connection - The database connection
         */
        public function __construct(PDO $connection) {
            $this->connection = $connection;
        }

        /**
         * This method inserts a new department into the database
         * @param array $Params - Method Parameters
         * @return array $AddRetval - Method Return value
         */
        public function add(array $Params): string {
            $SQLVars = ['department' => $Params['department']];
            $SQLStatement = "SELECT id FROM " . strtolower($Params['db']) . "_departments WHERE department=:department";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute($SQLVars);
            if ($SQLResult->rowCount() > 0) {
                return false;
            }
            $SQLStatement = "INSERT INTO " . strtolower($Params['db']) . "_departments SET department=:department;";
            $this->connection->prepare($SQLStatement)->execute($SQLVars);
            return $Params['department'];
        }

        /**
         * This method returns a list of departments
         * @param array $Params - Method Parameters
         * @return array $ListsRetval - Method Return value
         */
        public function lists(array $Params): array {
            if (isset($Params['id'])) {
                $SQLVars = ['id' => $Params['id']];
                $SQLStatement = "SELECT department FROM " . strtolower($Params['db']) . "_departments WHERE id=:id";
                $SQLResult = $this->connection->prepare($SQLStatement);
                $SQLResult->execute($SQLVars);
                return $SQLResult->fetch(PDO::FETCH_ASSOC);
            }
            $SQLStatement = "SELECT * FROM " . strtolower($Params['db']) . "_departments ORDER BY id";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute();
            return $SQLResult->fetchAll(PDO::FETCH_ASSOC);
        }

        /**
         * This method will remove a department from the database
         * @param array $Params - Method parameters
         * @return string $RemoveRetval - The name of the department removed.
         */
        public function remove(array $Params): string {
            $SQLVars = ['id' => $Params['id']];
            $SQLStatement = "SELECT department FROM " . strtolower($Params['db']) . "_departments WHERE id=:id";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute($SQLVars);
            $SQLReturn = $SQLResult->fetch(PDO::FETCH_ASSOC);
            $SQLStatement = "DELETE FROM " . strtolower($Params['db']) . "_departments WHERE id=:id";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute($SQLVars);
            return $SQLReturn['department'];
        }


       /**
         * The method update all fields in a department record
         * @param array $Params - Method parameters
         * @return array $ReplaceRetval - The method results
         */
        public function replace(array $Params): array {
            $SQLVars = ['id' => $Params['id'], 'department' => $Params['department']];
            $SQLStatement = "UPDATE " . strtolower($Params['db']) . "_departments SET department=:department WHERE id=:id";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute($SQLVars);
            return $this->lists($Params);
        }

        /**
         * This method will change the name of a department in the database
         * @param array $Params - Method parameters
         * @return array - Call success status with message
         */
        public function update(array $Params): array {
            $SQLVars = ['id' => $Params['id'], 'department' => $Params['department']];
            $SQLStatement = "UPDATE " . strtolower($Params['db']) . "_departments SET department=:department WHERE id=:id";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute($SQLVars);
            return $this->lists($Params);
        }

        /**
         * This method will check if a department is in the database
         * @param array $Params - Method parameters
         * @return boolean Method result
         */
        public function check(array $Params): bool {
            $SQLVars = ['department' => $Params['department']];
            $SQLStatement = "SELECT * FROM " . strtolower($Params['db']) . "_departments WHERE department=:department";
            $SQLResult = $this->connection->prepare($SQLStatement);
            $SQLResult->execute($SQLVars);
            if ($SQLResult->rowCount() != 0) {
                return true;
            } else {
                return false;
            }
        }
    }